Semiconductor substrate processing apparatuses are used for processing semiconductor substrates by techniques including, but not limited to, plasma etching, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), ion implantation, and resist removal. Semiconductor substrate processing apparatuses include gas delivery systems through which process gas is flowed and subsequently delivered into a processing region of a vacuum chamber of the apparatus by a gas distribution member such as a showerhead, gas injector, gas ring, or the like. For example, the gas delivery system can be configured to supply process gas to a gas injector positioned in the chamber above a semiconductor substrate so as to distribute process gas over a surface of the semiconductor substrate being processed in the chamber. Current gas delivery systems are constructed from many individual components, many of which have conduits therein through which process gas flows. The interfaces between individual components utilize seals therebetween such that leaking does not occur when process gas is being supplied through the conduits of the assembled gas delivery system.
Many components of a gas delivery system are formed from metal, such as stainless steel. A seal between components can become corroded and leak, which may lead to failure of the individual components and contamination of semiconductor substrates during processing thereof. For example, plasma gases used for ETCH processes react with stainless steel components leading to corrosion, which can cause low yields and poor performance of semiconductor devices. Corrosion compromises gas purity and quality of semiconductor devices. For instance, hydrogen bromide gas (HBr), in the presence of ambient moisture, can create a strong acid and start the corrosion process, according to the chemical reaction ½O2+2HBr+Fe=FeBr2+H2O on stainless steel. Thus, there is a need for predicting and detecting the beginning of leaks and corrosion, in order to prevent major failure of components or contamination of semiconductor substrates.